Anti-Aircraft Defence

This page looks at anti-aircraft policy in respect of the front line Home Defence battalion – not Heavy Anti-Aircraft defence. Troops on the ground could only engage low flying enemy aircraft with rifles or light-machine guns (lmg’s). At low levels such weapons are of value as they can traverse an arc much quicker than heavier guns.

In battalion Defence Schemes which mention an anti-aircraft policy, it is often stated that only troops actually being attacked by aircraft will open fire. This was for two reasons:

1) To prevent giving away the location of troops unnecessarily
2) To prevent the waste of ammunition

For example, 2/8 Lancs AA policy was that all fire is to be controlled and care taken not to engage enemy planes out of range (i.e. at a maximum of 1,800 ft). Forward platoons were to only open fire in daylight and if no enemy attack was expected so that ammunition expended could be replaced. If air attack was part of a combined landing, anti-aircraft fire was to be from rifles only. For this purpose, slit trenches were to be dug near each section post.

The Defence Scheme of 7th Manchester’s states that slit trenches were to be dug at right angles and at least 20 yards from section posts in order not to give away the post locality. The slit trenches should be dug to enable two or three rifle men to engage low flying aircraft. The 9th Lancs Defence Scheme also mentions that AA positions should not be near positions to be occupied on ‘Action Stations’.

It was also recognized that troops employed in constructing defensive works were vulnerable to low flying aircraft attack. The Defence Scheme of 1/6 South Lancs states that all Brens were to be deployed in their AA role during employment on defensive works. Again these AA posts were to be at least 200 yards from the posts they were defending so they could not be identified from the AA post. Fire was only to be opened if the aircraft was in effective range i.e. 600 yards or less. The Defence Scheme of the 9th Cameronians also notes that there should be an AA post per platoon or working party.

The Defence Scheme of 1st Liverpool Scottish is of particular interest on its comments on AA defence. It states that experience in Holland showed that lmg AA posts stood little chance against low flying aircraft attacks unless well concealed. It stated that concealment was of prime importance even if it was at the expense of limiting fields of fire. It also noted that as soon as the white upturned faces of lmg crews were noted they were attacked – consideration should be given to blackening the faces of AA crews.

15th Division also had a policy to address certain weather conditions favorable to low flying aircraft attack i.e. a cloud height of 600-1,000 ft. On anticipation of such conditions the code word ‘Cosmic’ was to be issued followed by the expected time of the weather condition. Until either dusk, a noticeable change in weather conditions or the code word ‘Cosmic off’ was received all AA lmg’s were to be fully manned. It was also made clear this was a 15th Div arrangement only and that the code word would not be issued to troops not under 15th Div control.

Finally, each battalion HQ Company probably would have had an AA platoon (usually No 2 platoon) – the Defence Scheme of 11th HLI notes the role of No 2 Platoon as AA protection for battalion HQ.

Method of providing small arms fire against aircraft :-

Small arms AA fire was only effective at low flying aircraft within 2,000 ft and at 600 yards distance. Low flying aircraft attacks would be over quickly (although may be repeated) allowing only three or four seconds of effective fire. At the start of the war, the normal method of firing lmg’s in the AA role was from some form of mounting, e.g. the Bren tripod could be set up in an AA role. Later in the war, shooting from the hip (the hosepipe method) was adopted as it was recognized that for effective all round defence it was better for the gun to move around the man (as in the hosepipe method) rather than the man around the gun (as for a lmg on a mount). The hosepipe method also required a smaller weapons-pit than an lmg on a mount. The hosepipe method did however rely on the observation of tracer, if this was not available the lmg would have to be aimed either by firing from the shoulder or a mount. Rifle fire was to be at rapid rate with sights set at 500 yards.

Hosepipe method - gunner firing from the waist in a Gunners taught to observe the stream of tracer when using the
weapons-pit hosepipe method. The apparent curve is an optical illusion.
Insead, gunners should concentrate on the target and observe
tracer flashing past or into the target

As well as active defence, outlined above, passive defence measures (i.e protection/cover against air attacks) were also put in place. This was basically the provision of slit trenches. Notes attached to the War Diary of 1st Liverpool Scottish detail the effective use of slit trenches by the BEF in France - apparently not a single man in their division was killed by a dive bomber while sheltering in a slit trench. These same notes also state that arrangements were in place for the RAF to tour the country and give troops some experience of what dive bombing looks like and accustom them to the noise! Virtually every Defence Scheme states that slit trenches are to be provided at all headquarters and billets.

Protection against air attack was also provided in section posts. For example 1st Liverpool Scottish Operational Instruction no 16 states that overhead protection should be provided in all section posts. Overhead cover of corrugated iron with two layers of sandbags was considered bullet proof.